A closer view, and the spider has moved a bit so you can see both his pedipalps (as you can see, enlarged at the ends, but still undifferentiated) and one of his curving fangs, which kind of folds under the chelicera like a jack-knife.

A hole about 1cm across in a metal railing. A juvenile male leaf-curling sac spider looks out from a sheer silk shelter (say that 5 times fast). He is a yellowish colour with a darker face and chelicerae (fangs).